Make more fixes and improvements

- Remove PAGESIZE constant
- Fix realloc() documentation
- Fix ttyname_r() error reporting
- Make forking more reliable on Windows
- Make execvp() a few microseconds faster
- Make system() a few microseconds faster
- Tighten up the socket-related magic numbers
- Loosen restrictions on mmap() offset alignment
- Improve GetProgramExecutableName() with getenv("_")
- Use mkstemp() as basis for mktemp(), tmpfile(), tmpfd()
- Fix flakes in pthread_cancel_test, unix_test, fork_test
- Fix recently introduced futex stack overflow regression
- Let sockets be passed as stdio to subprocesses on Windows
- Improve security of bind() on Windows w/ SO_EXCLUSIVEADDRUSE

third_party/python/Lib/socket.py

@@ -904,7 +904,6 @@ if __name__ == 'PYOBJ.COM':
     SO_PEERCRED = 0
     SO_PEERSEC = 0
     SO_PRIORITY = 0
-    SO_PROTOCOL = 0
     SO_RCVBUF = 0
     SO_RCVLOWAT = 0
     SO_RCVTIMEO = 0